For the mounting of optical elements in semiconductor components, cavities set at an angle, having an essentially rectangular contour, are used. Such cavities make it possible to tilt the bearing surface of the optical elements relative to a surface of the component. Here, the component can for example form an inclined window seat for an optical window. Angled cavities can be produced in a silicon substrate using subtractive processing methods (for example abrasively).
The article “Etching Methodologies in <111>-Oriented Silicon Wafers” (Oosterbroek et al., Journal of Microelectromechanical Systems, vol. 9, no. 3, p. 390-398, September 2000) describes a method for forming cavities in a silicon substrate. Through anisotropic etching of a substrate, cavities can be produced whose side surfaces are situated completely in {111} planes.